cp's OEIS Frontend

A168588 Smallest p(n)-digit prime with digit sum n, and made up of digits 0 and 1 only, where p(n)=A000040(n) (or 0, if no such prime exists).

%I A168588 #6 Feb 01 2021 13:21:51
%S A168588 0,101,0,1011001,10000110011,0,10000000010101111,1000000000001111111,
%T A168588 0,10000000000000000101101111101,1000000000000000000011111110111,0,
%U A168588 10000000000000000000000000011111111110101,1000000000000000000000000000110111111011111
%N A168588 Smallest p(n)-digit prime with digit sum n, and made up of digits 0 and 1 only, where p(n)=A000040(n) (or 0, if no such prime exists).
%C A168588 a(3n) = 0.
%H A168588 Robert Israel, <a href="/A168588/b168588.txt">Table of n, a(n) for n = 1..168</a>
%p A168588 g:= proc(L) local i,m;
%p A168588   m:= -1;
%p A168588   for i from 1 do
%p A168588      if L[i] = 1 then
%p A168588        if m = -1 then m:= i fi;
%p A168588        if L[i+1] = 0 then
%p A168588          return [1$(i-m),0$(m-1),0,1,op(L[i+2..-1])]
%p A168588        fi
%p A168588      fi
%p A168588   od
%p A168588 end proc:
%p A168588 f:= proc(n) local L,x,pn,i;
%p A168588   if n mod 3 = 0 then return 0 fi;
%p A168588   pn:= ithprime(n);
%p A168588   L:= [1$(n-1),0$(pn-n),1];
%p A168588   do
%p A168588     x:= add(L[i]*10^(i-1),i=1..pn);
%p A168588     if isprime(x) then return x fi;
%p A168588     L:= g(L);
%p A168588   od
%p A168588 end proc:
%p A168588 map(f, [$1..16]); # _Robert Israel_, Feb 01 2021
%Y A168588 Cf. A036929
%K A168588 nonn,base
%O A168588 1,2
%A A168588 _Lekraj Beedassy_, Nov 30 2009
%E A168588 Extended by _Ray Chandler_, Dec 03 2009